A typical microfluidic channel system mainly includes a substrate which is made of glass transparent plastic material and is etched by complicated development etching processes to form grooved microfluidic channels on a surface thereof. Moreover, a basic structure of the microfluidic channel system can be assembled by using another substrate to cover thereon. This type of microfluidic channel system is widely used as a carrier of detections for optics, electrochemistry, and electrochemical electrophoresis analyses.
For example, Taiwan patent No. 1294968 reveals a bio-electrical detection chip, which includes a chip body, a first microchannel, a second microchannel, and a pair of working electrodes. The first microchannel, the second microchannel, and the pair of working electrodes are disposed on the chip body, and the first and second microchannels penetrate through the chip body. The first microchannel is interconnected with the second microchannel. The first microchannel is utilized to guide a sample fluid to flow; the second microchannel is utilized to guide a buffer fluid to flow. The two working electrodes are disposed at both sides the second microchannel, respectively, thereby performing a non-contact electrophoresis analysis.
However, the drawback of the grooved microfluidic channels within the conventional substrates is that surface tension or viscosity of the microfluid influence a capillary action of the microfluid and a rate of the flow along a pipe wall of the microfluidic channel. Furthermore, the greater the surface tension or viscosity, the greater an adhesion force of on the pipe wall is; the longer a flowing duration is.
Thus, it is prone to the problem of poor fluidity. Moreover, if a voltage is applied to the microfluid in the grooved microfluidic channels for carrying on electrochemical analyses such as capillary electrophoresis, a Joule heating effect is easy to generate in the microfluid within the grooved microfluidic channels, thereby affecting a variety of background parameters and accuracy of the experimental results. In addition, if the purpose of the experiment is changed, the shape of the grooved microfluidic channel also needs to be re-fabricated by the complicated development etching processes. Thus, its overall analysis and detection cost is relatively high.
In the channels of the conventional electrophoresis chips, because the substrates are mainly made of glass and polymer organic transparent silicon compound, and because lengths of an injection channel and a separation channel are fixed due to its manufacturing processes, injection volume that is used for separating the sample can not be changed quantitatively. As a result, the analyzed sample which reaches a detection end is a very small amount, resulting in a poor signal to be obtained, or it is not easy to be detected. Therefore, the present system is developed by twining different number of turns of coils, thereby changing the fed amount of the sample in order to achieve a high detection sensitivity.
Therefore, there is a signification need to provide an improved microfluidic guiding system for solving the problem existing in the structure of the conventional grooved microfluidic channels.